The present invention relates to a microprocessor-controlled servo device for holding, carrying, and moving a camera, and more particularly to a device, which comprises a microprocessor chip processing control circuit, and I/O port and a servo set, for controlling and moving a camera.
Two kinds of servomotors available on the market are AC or DC servomotors for industrial automation and radio controlled DC servomotors. The structure and control of industrial servomotors is complicated, for the reason that the control accuracy requirement is high. Even a standard normal class needs 1 mm accuracy. When such kind of motor is used for carrying and moving a camera, the occupied space is relatively large and the cost is high. The operation and settings depend on professionals and use and maintenance is relatively complicated. The photographing angle of a normal camera with a standard lens is at a vision angle of 40 to 50 degrees at most. But even a difference in vision angle of 100 mm in the image taken by the above-mentioned camera is not very important. The usual field of application for the industrial servomotor is in industrial automated precision mechanical facilities, and not in camera monitoring.
A servomotor used by a normal radio controlled toy is used in such things as a radio controlled airplane, boat or car. Such kind of servomotor comprises an input control signal, driving amplification circuit, DC motor and potentiometer. The input control signal is a positive pulse control signal emitted from a radio transmitter operated by a user. The frequency range is approximately 27 MHz or 40 MHz according to the country and the area. The driving amplification circuit is manufactured into an IC in most products made by advanced countries such as the United States, Japan and Germany. The driving amplification circuit receives the positive pulse control signal transmitted from the radio transmitter and drives a DC motor to take a forward or backward rotation or to stop after a comparison operation. The motions of the servomotor are of only three types: forward rotation, backward rotation, and stop. The forward and backward rotations must be processed by using an operator""s hand to move an operating shaft constructed with the potentiometer back and forth. The servomotor rotates forward when the shaft is moved forward, and rotates backward when it is moved backward. The shaft automatically springs back to the middle position when the operator takes their hand away, and the servomotor stops. Its motion is simple enough to be fit for using for the operation of a normal manual remote controlled toy. Also, because its motion is too simple, the function thereof is not enough for practical use to be used for moving a camera in order to perform circumstance monitoring. Therefore, it must be revised. Moreover, the rotating angle of its forward and backward rotations is limited by the structure of the servomotor. The largest rotating angle it can rotate is 60 degrees or so. Such kind of angle ranges can be utilized flexibly in the field of radio controlled toys, but it will obviously form a dead angle in camera monitoring owing the deficiency in the rotating angle of the camera when used for carrying and moving a camera. Because the monitoring operation is manual instead of automatic, it is difficult to apply in practical use.
Another radio controlled servomotor is available now which comprises a DC motor, a deceleration gear set, a potentiometer and a driving circuit. The main shaft of the DC motor is connected with the rotating shaft by means of a gear set. The rotation of the DC motor also drives the potentiometer to rotate. The rotating shaft of the potentiometer is lengthened to extend out to be taken as a loading main rotating shaft of the servomotor. Therefore, for the reason that the loading main rotating shaft is limited to both the rotating angle range of the potentiometer and the rotation structure of the potentiometer itself, it has a limited rotation range, i.e. the total rotating angle is about 120 degrees. Consequently, it is quite difficult to expand the rotating angle range of the DC motor to be twice thereof or even close to 360 degrees. The radio controlled servomotor can only be used in toys and is in no way to be used for carrying and moving cameras. It has two deficiencies in practical use. One is that the motions that can be operated are of only three kinds: forward rotation, backward rotation, and stop. These motions must be made manually. Another deficiency is owing to the deficiency of the rotation structure of the potentiometer itself, which causes the total rotating angle plus approximately 10% error to be only about 120 degrees. It has no way of effectively conquering the dead angle for camera monitoring.
Thus, it can be seen that the use of the above-mentioned traditional art servomotor applications are not effective or convenient for carrying and moving a camera in order to perform camera monitoring. Therefore, improvement is necessary.
An object of the present invention is to provide a camera with a function memorizing a plurality of preset point positions. This enables the camera to automatically jump to do tracking photography from a first position point to an nth position point in sequence according to the preset time period when the microprocessor control processing system receives xe2x80x9ca plurality of preset points automatic trackingxe2x80x9d command. The preset time can be input and set by an input control button.
Another object of the present invention is to provide a camera with a function for memorizing a position after the position is correctly adjusted. This enables the camera to take a forward rotation or backward rotation whenever necessary to as to choose locations that need to be photographed, when the microprocessor control processing system receives xe2x80x9cforward rotationxe2x80x9d or xe2x80x9cbackward rotationxe2x80x9d commands.
Still another object of the present invention is to provide a camera with a function that can memorize the N positions after the positions are adjusted correctly. The camera can memorize N memory points of the present positions at any time through the operation function selection of the input control and memory button, when the microprocessor control processing system receives a xe2x80x9cmemoryxe2x80x9d command.
Another object of the present invention is to provide a low-speed tour programming function. This enables the camera to process the motion tour programming camera monitoring from a first to an nth memory location point according to the preset programming speed in the preset N memory position points, when the microprocessor control processing system receives a xe2x80x9cprogrammingxe2x80x9d command.
Another object of the present invention is to provide a function for abnormality invasion. The camera can automatically track to the position point of preset memory designated by a termination input function and lock on the target in order to process photographing and emit alarms signals when the microprocessor control processing system receives a xe2x80x9ctermination emergency inputxe2x80x9d command.
Another object of the present invention is to provide a display, such as an LCD, enabling an operator to see whether the input commands and data are correct and to monitor the system execution states.
The present invention utilizes at least two methods to overcome the disadvantages of the prior art. One is to use a microprocessor processing control system to generate a corresponding control signal. Another is to use an improved servo set.
The microprocessor single chip processing control system of the present invention comprises single chip control circuits and corresponding software. The single chip control circuit also has a supply power and clock pulse generating circuit needed for the single chip. It comprises an input signal operating keyboard, a single chip, memory, an LCD and I/O ports. Its function is to generate a corresponding control pulse signal automatically. The corresponding software program, mainly stores corresponding data about locating positions of the deceleration DC motor of the servo set and the program executing a series of commands into the memory. A rotation range so that the deceleration DC motor rotates 360 degrees effectively is L. L is divided into N equal parts. Each different equal part has a corresponding control pulse signal as it representation. The pulse widths T for all pulse signals are different. For example, a pulse width corresponding to the first starting point position Ls of the effective range L, is Ts. A pulse width corresponding to the middle point position Lm of the range L, is Tm. And a pulse width corresponding to the end position Le, is Te.
For an example, in a preferred embodiment of the present invention, the whole range is Cut into 1400 equal parts so the corresponding 1400 different pulse widths, T*1400, will be stored in the memory. When an operator inputs an input signal or external termination control signal, the microprocessor chip will read the relative data input into memory. The input control pulse width must be in the opposite direction with the pulse width of the reference pulse signal generated by the servo set so as to add their difference and output the differential pulse width. The description concerning the differential pulse width on the rotation servo will be described later.
The servo set comprises two servos, which rotate horizontally and perpendicularly respectively. One of them holds and moves a camera. Each servo comprises a deceleration DC motor, a meshing gear set, a motor main shaft, a potentiometer and a driving circuit. The main shaft of the deceleration DC motor and the rotating shaft are connected by the meshing gear set. This enables the deceleration DC motor to drive the potentiometer to rotate. In order to let the rotating angle of the deceleration DC motor to be larger than the angle of the rotation range of the potentiometer, the teeth number of the meshing gear meshed with the main shaft of the motor is larger than the teeth number of the meshing gear meshed with the rotating shaft of the potentiometer. In other words, when the motor rotates a unit distance, the rotation of the potentiometer is smaller than the unit distance. Therefore, it enables the motor to rotate larger than or equal to 360 degrees, and not to be limited to the mechanical structure limitations of the potentiometer which makes the rotation absolutely smaller than 360 degrees.
The following describes how the differential pulse width signal influences the rotation of the servo. Each servo moreover pairs with a set of driving circuits. The driving circuit comprises a pulse comparator, a pulse amplifier, a motor driver, and a reference pulse signal generator. The function is that when a control pulse signal generated from the microprocessor chip processing control circuit is input, the reference pulse signal generator is triggered to generate a reference pulse signal in the opposite direction with the control pulse signal. After the pulse widths of these two pulses are compared in the pulse comparator, a differential pulse width signal, that is the difference between them, is generated. If the differential pulse width is a positive pulse width, the deceleration DC motor takes a forward rotation through the driving amplification of the driving amplification circuit. Alternatively, if the differential pulse width is a negative pulse width, the deceleration DC motor takes a backward rotation through the driving amplification of the driving amplification circuit. If the differential pulse width is equal to zero, it means that the two pulse widths are equal, and no signal is processed in the driving amplification circuit, then the DC motor will stop rotating.
The camera driven and moved by the device of the present invention, provides a camera monitoring capable of position memory, tour programming, alarm output, and automatic tracking.
The LCD display can let an operator see whether the input commands and data are correct and monitor system execution states.